The monitoring of control units in a network is described in PCT Published Patent Application No. 90/09631 (corresponding to U.S. Pat. No. 5,499,366). This publication describes a method of monitoring a computer network having at least two subscribers connected by a databus having at least two lines, each having a receiving component and/or a transmitting component. This method is characterized in that the function of the databus and/or the subscribers is monitored with the help of error detection signals of at least one subscriber, and emergency operation measures tailored to the given error case are taken to establish defined emergency operation modes. After the first emergency operation measure has been taken, a check is performed to determine whether the computer network is functioning free of errors. If this is the case, the first emergency operation measure is maintained and also the emergency operating mode achieved with it is maintained. If, after the first emergency operation measure has been taken, additional errors occur in the computer network, the first emergency operation measure is cancelled and the second emergency operation measure is taken. If no additional errors then occur, the emergency operating mode established through this measure, special emergency operation, is maintained. Only if additional errors continue to occur are the respective subscribers or the entire computer network shut down. The cited patent does not describe the use of a shutdown matrix or a differentiated shutdown having different shutdown strategies.
Therefore, in the case of monitoring a plurality of control units in one network, i.e., in a distributed system, the situation described above is to be improved by implementing a more differentiated shutdown of individual control units or the system as a whole by using a shutdown matrix.